percentage
by Ushinatta Neko
Summary: There's nothing better and nothing worse than being the best friend of your brother's crush. — RinMikuLen, sibling rivalry.


_A/N: I got my hands on the Happiness and Peace of the Mind Committee series so I came back (even though it's only the first three...lol)! The books were great. 10/10 recommend if you can read Chinese/Japanese. It got me back to writing Vocaloid fics and hey, since I've never written about my OT3 I thought I would give it a go._

 **Disclaimer: I don't own Vocaloid.**

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Halfway through the movie, Kagamine Rin looks over at the two people most important to her. And finds something shocking.

Out-of-the-world shocking.

"Len! That's my ice cream! Give it back!" She mock-gasps in horror, and her brother rolls his eyes. He ignores her freakish outburst and continues to scroll down his phone, looking at the news. He also ignores her claim on _her_ ice cream (that she bought after a ten-minute walk to the convenience store, thank you very much) and continues eating.

She reaches over and slaps her brother on his back and demands it back. "You ass, I walked for it! I paid for it! And you just took advantage of my work and ate it!"

"That was a week ago, Rin. And you still didn't eat it, so I thought it was free territory," Len hisses, and rubs the back of his shoulder. Rin knows how much strength she has and right now, she wants nothing more than to give him a punch right into his stomach.

"Miku, back me up on this! You _know_ what happened during the week!"

"It's still free territory, Miku."

Both Rin and Len turn to the girl sitting in the middle for help and the final judgment.

Miku smiles awkwardly, unsure of what to do. Like her seat on the sofa, she's caught in the middle of their banter and _more_. She puts her legs down from their cross-legged position on the couch, and fiddles with her fingers.

"Rin, Len," Miku starts, but blushes for a lack of explanation. She twirls her long hair around her index fingers, no doubt thinking of how to word this appropriately.

Rin knows her best friend would take her side in matters like these. She just knows.

Sure enough, Miku takes a deep breath and continues. "Len...how do I put this. Rin had some issues over the past week which resulted in her being unable to enjoy her ice cream. So it's not technically free territory."

"Oh yeah? Like what?" Len replies, his snarky tone beckoning challenge. But Miku blushes heavily and even the tips of her ears turn red, and Len realizes too late what she means.

Meanwhile, Rin explodes into a protective cover for Miku.

"She means my _period_ , you ass whack! How dare you make Miku undergo this humiliation! And give my ice cream back as redemption!" She snatches the melting ice cream from her brother's limp hand and stuffs it into her mouth in triumph and victory.

She also snatches Miku away from the movie and the couch and Len's side, and, taking ahold of Miku's warm fingers, makes a face at her brother.

"Come on, Miku. We have no need to stay with this ice cream thief any longer. Good-bye!" Rin turns and flounces off to her room at the end of the corridor. Before, she had wanted to sink her fist into her brother's stomach (but now she would like nothing more than to take Len away from her best friend). Her face heats as she wraps her fingers around Miku's slim wrist and she's sure Miku can see how red her earlobes are, but Miku is busy giving Len sorry glances and he is returning them (and Rin's heart twists into an ugly pretzel).

They finally reach her room and Rin slumps into her bed in relief. Her heat untwists cautiously now that her brother is no longer with them.

Miku keeps stealing glances at the door and from far away, her brother's voice rings sulkily. " _You_ brought it up, not me!"

Rin rolls her eyes. Of course she did. There is a pause before Len shouts again. "And I didn't want to know about your period anyway!"

"We really should finish the movie," Miku addresses Rin but her eyes flit towards the door. (Rin notices.) She hums in reply but makes no move to get up, and Miku concedes defeat and sits down. She starts reading through some of the poetry Rin has on her table and there is a comfortable silence floating over the two of them.

Rin wants to ask Miku about her views on Len, but the question lodges itself in her throat and refuses to climb out. She doesn't want to know, but she also wants to know. Miku is Miku, after all, her adorable _best friend_ with the most adorable voice ever, and Len...is, well, Len. He's her younger _brother_ , and her blood relative. Rin has to twist the bed sheets to remind herself of that fact. Her stomach twists by itself as well, as if further reinforcing that truth.

Either way, she feels like asking might destroy the delicate ice they are all dancing on, and she doesn't want that. No matter that she's the one who had created that thin layer of ice in the first place.

But Miku is the one who brings up her question, as always. Miku's always been braver than Rin thinks she would be in spite of her petite stature, and Rin always forgets to give her credit for that.

"Rin, would you mind if I asked Len out?" She asks hesitantly, though her grass-green gaze unwavering. But Rin notices her cheeks are awash with pink. It must be awkward to ask for permission to date her brother. Like how Rin feels like right now but _less_. If her heart is a pie chart _feeling hurt_ would be filling up fifty percent of the circle and _jealousy_ the other fifty.

"Sure, go ahead. I don't mind." Her fingers tremble and Rin lies through her smile and the ugly beast rearing in the deepest recesses of her heart.

Miku only nods, but her eyes never leave Rin's. As if she knows. But she can't, can she?

Rin keeps on smiling, her cheeks stretching to fit in all her lies, even when she watches from the doorstep (as usual) as Miku asks Len out for a date.

Len remains unquestionably excited throughout the week and Rin turns sour. It doesn't show on her face, of course not, because how could she let it show? Len's her _brother_ and Miku's her _best friend._ She's _supposed_ to be happy.

She worries herself sick three days before Len and Miku's date at the park.

Miku comes over to visit and pops her head in cautiously. "Rin?" Her voice is soft and her eyes even softer. "I brought mandarin oranges. The organic ones that you like."

Rin wants to say _thanks_ but what comes out instead is a warbling croak and she blushes. The towel on her forehead slips and Miku hurries over to catch it. Her fingers brush against Rin's forehead as she adjusts the cold towel and Rin sighs in relief. (Quietly.)

"It's a wonder that you get sick so often. I thought oranges were good for your health." Miku frowns down at her but her hands are working on the oranges and Rin smiles expectantly even though she's sweating heavily. Behind Miku her bedroom door cracks open silently and Len comes into view. He watches their interactions from his station behind the door.

Rin shoots her brother a winning smile as Miku feeds her a slice of orange and Len's face is sulky as the thunderclouds in her heart. They're still going on a date and there's nothing Rin can do to stop them.

After her _best friend_ leaves with a goodbye for Len Rin slides out the heat pack under her shirt and throws it in Len's face. He catches it, though, and fixes her with a glare that Rin returns.

"I win," she announces as she removes the towel from her forehead. Len gives her the patented Kagamine Len Eye Roll.

"I'm the one going on a date, Rin." He pauses before adding on, his hand stroking his left cheek. "And before she left she kissed me on the cheek. Which she won't ever do for you."

Rin throws her dictionary at her brother's head but he closes the door and the dictionary slams against the wood before falling on the floor with a thump.

Vinegar brews in her throat and she wants to kill someone.

Len leans against her doorway the day before his date and plasters on a neutral smile. He's holding his cup, Rin realizes with a start.

"Rin." Len glares at her and then at the bottom of his cup. "Are you trying to get me sick?"

"No," Rin flips through her magazine nonchalantly.

"Then stop spitting into my cup!" Len runs his fingers through his hair and Rin notices that he has acquired this habit from Miku. Miku always runs her fingers through one of her ponytails when she's frustrated.

But Rin's hair is too short to do that so she can't.

She remains silent as Len fiddles with his cup and seems to realize something. He turns to her with a disbelieving look in his face as the cup in his hands dangle dangerously.

"You're trying to sabotage our date, aren't you?"

Rin shrugs and her brother fumes, leaving. He slams the door as he goes and their mother shouts from below to _keep it down!_

But Rin doesn't. On the day of their date she smiles widely, dressed in her favourite blouse and skirt, as she watches Len give her the deadliest glare she has ever seen. Somewhere her conscience shrivels into a shell but Rin still smiles, shaking with thrill.

"I'm going to kill you, Rin Kagamine." Len snarls before dashing to the restroom. Rin follows and knocks politely on the closed restroom door. Her brother's voice stabs through the wood as he asks _what the hell do you want?_

"'All's fair in love and war'," Rin quips. "We know I don't have a chance with her. We also know that there is a very high chance that Miku is going to confess to you after today's date. So let me enjoy the last days of her _single_ status. You're my brother but I don't want to see you with her. Not yet, anyway."

She knows she probably doesn't deserve begging him like that, not while he's sitting on the toilet bowl, courtesy of the diarrhea pills she slipped into his morning milk, but she's so _desperate_ , and desperation drives people to do things. Len is silent in the small cubicle, but Rin knows that she wouldn't go ahead without his permission. He's still her brother, no matter how much she hates him for making Miku fall for him.

"Don't try anything funny," he finally grumbles out and Rin smiles at the door.

"I won't!" She shouts as she flies through the front door and behind her, Len shouts back.

"I'm serious!"

So is she.

Rin meets Miku at her house and Miku is obviously surprised to see her. Rin's cheeks are flushed but she's sure that it's not because of running. "Len," she gasps through her stitch. "Len's sick. He ate something bad."

Miku's face falls and Rin just notices the summer dress that her _best friend_ (and _crush_ ) has put on. For Len. Her own smile almost peels from her face with a painful _rrip!_ but Rin hurriedly plasters it back on. "He told me to run over as fast as I can to tell you." Rin pauses and watches Miku slowly nod in understanding, probably thinking about _how considerate he is!_ Vinegar spreads throughout her mouth again but she gulps it down.

"So um," her voice fumbles as it dimly registers in her mind that it would be a _date_ for her. "Do you want to hang out with me instead? I'm free today too."

Miku cocks her head to the side and considers, while Rin crosses her fingers behind her back and hopes beyond hoping that her answer is yes. She feels like a young teenager confessing her love to her crush, which she technically is, but they're _friends._ Best friends.

"Sure." Miku smiles like a friend would and Rin's heart flutters in conflict. She runs up and hugs her, and Miku's grassy scent fills her nose. It's a relaxing fragrance and before she can think about it, she presses her lips against Miku's cheek. It's only an instant but she can feel how silky smooth Miku's skin is and when her lips leave her cheek, Rin's ears are red.

Miku only laughs and hugs her back. Rin almost stutters an apology but then there is a pair of lips upon her own cheek and she stiffens. Miku pulls away and laughs even more, her own cheeks red as an apple. Her lip-gloss shines in the morning sun. She obviously thinks that it's a prank, and Rin pretends to sulk to let her think so.

But her hand sneaks up to her cheek and she can feel the imprint of Miku's lips and her lip-gloss. Her heart is a strange mixture of thirty percent vinegar and seventy percent honey. She doesn't know what to think, because even though this is a kiss it is only a kiss and nothing more.

It's a hundred percent kiss but zero percent love.


End file.
